1. Field of Invention
This invention relates generally to improvements in manufacturing gaskets for sealing components that interface with internal combustion engines, such as air intake manifolds. More particularly, the invention relates to improvements in designs of bottom intake manifold gaskets for providing thermal insulation between the interface of an engine cylinder head and an air intake manifold, as well as reduction in number of component parts involved in the manufacture of such gaskets.
2. Description of the Prior Art
Even though engines have become more robust with respect to sizes and horsepower demands in recent years, and in spite of the fact that under-the-hood operating temperatures have tended to increase, the use of plastic intake manifolds has proliferated. Simultaneously, there has been a significant increase in the use of under-the-hood electronic components, some extending into or protruding out of such plastic intake manifolds. As a result, there is constant and increasing pressure to achieve lower operating temperatures in the environment of plastic intake manifold structures utilized in new engines.
Moreover, it has been long recognized that plastic materials tends to degrade over time, particularly as a function of amount of heat to which plastic components are subjected. Thus, isolating heat transfer, especially between metal engine components and mating plastic components (such as between engine cylinder head and newer plastic manifolds), has become a continuing effort, if not a consuming passion, for various engine designers in the automotive world.
In addition to degradation of plastic materials when subject to high thermal inputs, plastic material warpage, with commensurate issues of creep and relaxation, work to impair sealing at various manifold ports or openings. The sealing aspect is particularly important for various components that directly interface with the manifold, such as mass airflow sensors. To the extent that metal carrier bodies have been the traditional material of choice for lower manifold gaskets, a major improvement in this art area would be well received, particularly as relating to gasket materials adapted to provide greater heat insulation and weight reduction.
Finally, the use of alignment grommets has been crucial for assuring proper placement of bottom intake manifold gaskets on cylinder head deck areas. Traditionally, such grommets have been formed separately, and have had to be assembled at the time of, or just prior to, placement of the gasket on a cylinder head deck. This has resulted in separate handling and stocking requirements of additional component parts, which could be eliminated if such grommets were formed as integral parts of the gasket carrier bodies.
A gasket for sealing an intake manifold of a dual cylinder head on an internal combustion engine is comprised of a plastic carrier having a pair of substantially planar surfaces that define top and bottom surfaces. The gasket includes a plurality of air intake apertures that extend between the surfaces. Each intake aperture has an elastomeric bead circumferentially bonded to the edges of the carrier. The edges define the interior boundaries of the apertures, and in the described embodiment include a series of small openings for mechanical attachment of the elastomeric bead to the plastic carrier.
The gasket includes primary and secondary compression limiters made of powdered metal in the described embodiment. The compression limiters are located, respectively, adjacent to bolt holes and symmetrically between air intake apertures. The gasket also includes flexible alignment grommets that assure positive alignment between cylinder head and intake manifold structures to be secured together. Each of the grommets is comprised of a frustum-like body and a cylindrical post, each extending outwardly of the top and the bottom surfaces of the gasket, respectively. The frustum-like body and post are sized and configured to mate with conical and cylindrical alignment depressions and/or openings in respective intake manifold and engine cylinder head. The converging walls of the frustum-like body portion are comprised of trapezoidal-like petals joined to the base of the frustum-like body, which permits radial flexing. The post, which is nominally located along the symmetry axis of each locator, is mounted to the base of the locator with flexible, radially extending spokes, which permit lateral flexing to assure proper alignment between cylinder head deck and manifold structures.